1. Field of the Invention
The present invention relates to a vehicle running control technique.
2. Description of the Prior Art
FIG. 1 is a view schematically illustrating a cause of torque steer occurrence in a conventional vehicle.
In a conventional vehicles, an engine is positioned in the front of the vehicle and a power train leans to one of left and right drive shaft 15a and 15b as shown in FIG. 1. Due to such a layout, in such a conventional vehicle, the lengths of left and right drive shafts 15a and 15b may become different from each other.
When drive torques are applied to the left and right drive shafts 15a and 15b in such a vehicle, different moments are applied to knuckles of left and right wheel sides 10a and 10b of the vehicles, respectively. Due to the difference of the moments, uneven torque is applied to the left and right wheel sides 10a and 10b and, thus, acts as a force that steers the vehicle.
That is, a phenomenon which causes the vehicle to lean to the longer drive shaft occurs.
Such a phenomenon is referred to as a torque steer. At a low speed state where the engine power is not high, the force that steers the vehicle is also small and, thus, the phenomenon is not remarkable. However, when suddenly starting the vehicle from a stopped state while driving force is being increased or when suddenly accelerating the vehicle while the vehicle is running, the torque steer phenomenon occurs and the vehicle is driven in a state where the vehicle body leans to one side.
Conventionally, it has been proposed to reduce drive torque at the time of initially staring the vehicle in order to prevent such a torque steer phenomenon. However, there is a problem in that, when the driving torque is reduced, the acceleration performance of the vehicle is degraded.